Tension regulating device



April 1961 J. B. YURYAN 2,981,498

TENSION REGULATING DEVICE Filed Nov. 5, 1956 2 Sheets-Sheet l April 1961J. B. YURYAN 2,981,498

TENSION REGULATING DEVICE Filed Nov. 5, 1956 2 Sheets-Sheet 2 2,981,498TENSION REGULATING DEVICE Joseph B. Yuryan, Hudson,

Taylor & Sons, Inc., Massachusetts Filed Nov. 5, 1956, Ser. No. 620,2729 Claims. (Cl. 242-154) Mass., assignor to Thomas Hudson, Mass, acorporation of i This invention relates to tension regulating devicesand has for its principal object to provide a device for regulating thetension in elongate flexible elements as they travel from a storagecontainer to a place of use, for example, strands or threads as theytravel to textile machines for incorporation into a fabric by weaving,braiding, and the like. Another object is to provide a device which willregulate the tension in an element whether it is of an elastic orinelastic nature. Another object is to provide a device which willregulate the tension of an elongate traveling element whether it is oneor more strands, cables, ribbons or sheets of single or multipleconstruction. Another object is to provide a device in which greatsensitivity at the input end may be obtained with very little feed-backfrom the output. Another object is to provide a device which respondsquickly to changes in tension so that no overfeed or tension lossesoccur. Another object is to provide a device for regulating tensionwhich can compensate for minor changes in surface conditions of theelement. Another object is to provide a device for regulating thetension in a traveling element which will compensate for any obstructionto free delivery from the storage at the input end and any irregularityin takeup at the output end. Another object is to provide a device inwhich surge and bounce clue to rapid movement of the elements may beminimized. Another object is to provide a device for adjusting the totaldrag available. Another object is to provide a device in which it ispossible to obtain ideal conditions of tension for splitting strandswhich have been rebonded thereby to prevent roll over and breaking.Another object is to provide a device for regulating the tension in atraveling element regardless of its intended use. Another object is toprovide a device for regulating the tension in a traveling element whichmay easily be interposed between the source of the element and themachine or place where it is to be fabricated or operated on.

For the purpose of simplification the element, regardless of itsmake-up, will be referred to hereinafter, as a strand.

As herein illustrated, the device comprises a plurality of parallel dragbars about which the strand to be tensioned alternately passes in adevious course, which bars are operably connected so that an increase inresistance to flow at the ingoing end or a decrease in the rate of flowat the outgoing end, decreases through the working of the linkageupward, the resistance to flow through the device; and vice versa, adecrease in the resistance at the input end or an increase in the rateof fiow at the outgoing end increases the resistance to flow by means ofthe downward working of the linkage. The drag bars are connected bytoggle links and are arranged vertically in a frame, one above theother, with the lowermost bar pivotally fastened to the frame and thealternate ones of the bars supported for vertical movement along trackson the frame. The intermediate bars at the knees of the toggle links arefreely floating so that extension of the States Patent '0 linkagedecreases the length of the courses of the strand and the wrap-aroundfriction as it passes alternately about the successive bars, andcontraction or collapse of the linkage increases the length of thecourses of the strand and increases the wrap-around friction as itpasses about successive bars. The weight of the linkage itself tends tocollapse it. However, other means may be arranged at the upper end totend to collapse the linkage in opposition to the tendency of the strandtraveling therethrough to extend it. There may be weights suspended fromthe top bar by eccentric means so that they reverse buckling so that thefloating drag bars will all lie on the same side of the guided dragbars. A fixed bar may be arranged spaced from and parallel to thelinkage at its lower end which, in conjunction with the pivotallyfastened bar and the first floating bar, provides for (10111 bling thestrand upon itself, thereby to increase the sensitivity of the device.Surging or bouncing of the linkage may be damped by still anotherauxiliary bar spaced from and parallel to the linkage at the oppositeside which is supported from the first of the toggles for verticalmovement therewith. This auxiliary bar provides means for receiving afloating loop of larger dimensions than would be possible to obtainabout the pivotally fastened bar. A limit bar is fastened to the frameadjacent the pivotally fastened bar in a position to support the lowermost one of the floating bars when the linkage is collapsed and tooperate in conjunction with the lowermost floating bar to provide apinch on the strand. Means may be applied to the upper bars of thelinkage to prevent maximum angular opening of the toggles and hence byconstraint of these bars affording a certain amount of adjustment of thetotal drag. Additional adjustment of the'total drag may be had by adouble drag bar at the input which is angularly adjustable to increaseor decrease the wrap about the fixed bar.

The invention will now be described in greater detail with reference tothe accompanying drawings wherein:

Fig. l is a vertical section of the device showing a continuous elementbeing delivered from a container to it and the course of the elementthrough the device;

Fig. 2 is a rear elevation of the device as seen from the right-handside of Fig. 1;

Fig. 3 is a vertical section through the device modified to increase itssensitivity and shows the linkage partially collapsed;

Fig. 4 is a corresponding section showing the linkage nearly extended;

Fig. 5 is a vertical section modified to provide for lesser internalresistance to flow when the device is fully extended;

Fig. 6 is a vertical section of still another modification provided withadditional means for increasing its sensitivity at the input end forminimizing surging;

Fig. 7 is a front elevation of the device as seen from the right-handside of Fig. 6;

Fig. 8 is an elevation in section showing the linkage at a position ofmaximum collapse;

Fig. 9 is a fragmentary elevation in section showing the stop lugs; and

Fig. 10 is an enlarged fragmentary elevation of the weight eccentric.

For the purpose of illustration only, the device illustrates regulatingthe tension on ribbon rubber which is made up of a plurality ofindividual strands of rubber rebonded by taking advantage of its naturaltack and which is being fed from a container to a textile machine forincorporation of the individual strands into a fabric; the device forthis purpose being provided with a splitting bar in the form of a simplewire or rod as will be dc? scribed hereinafter. For the purpose of thisdescription,

a ,3 however, the element being tensed will be referred to only as astrand.

As shown in Figs. 1 and 2, the tension device is a complete unit initself, havingits own supporting frame 12 which may be arranged betweena source of supply 14 of the continuous strand which is to be tensionedand the machine which is to operate on'thestrand. The frame 12 has abase 13 and spaced parallel uprights 15 and may stand on its own baseadjacent the machine or may be fastened to an appropriate part of theframe of the machine depending upon the availability of space and thebest location for feeding the strand to the machine. In its simplestform, as shown in Figs. 1 and 2, there is an expandable linkagecomprised of a plurality of spaced parallel, alternate drag bars 16a,16b, 16c -and.16d, and a plurality of spaced parallel intermediate dragbars 18a, 18b, and 180. The bar'sare connected by toggle links 20d-22a,20b--22b and 20c-'-22c. The lowermost of the bars 16a is pivotally.fastened in the frame 12 between the uprights 15, in fixed bearings,for example, bearing holes'in the-uprights so that the lower end of thelinkage is fixed. The remaining bars 16b, 16c and 16d are verticallymovable with respect to the pivotally fastened bar 16a along tracks 24,constituted by a pair of vertical slots in the uprights 15 of the frame12, through which their ends or prolongations thereof extend. The bars18a, 18b and 18c are freely floating at or near the knees of the togglesand are laterally displaced from the vertical plane of the bars 16a,16b, 16c and 16d by the degree of extension or collapse of the toggles.As will be seen by reference to Fig. 2, the upper ends of the togglelinks 20a, 20b and 200 are fixed to the bars 18a, 18b and 180respectively, and their'lower ends are pivotally connected to the bars16a, 16b and 160. The toggle links 22a. 22b and 220 are fixed at theirupper ends to the bars 16b, 16c and 16d respectively, and their lowerends are pivotally connected to the bars 18a, 18b and 18c. The paralleldrag bars are thus allowed to pivot 'freely about their link centers butare held parallel by the toggle link pairs which are locked to one'barbut pivoted about the succeeding bar. Since only the lowermost drag bar16a is pivotally fastened to the frame all of the others float up anddown the slots 2424 freely.

The tension is produced by the alternate wrapping of thecontinuousstrands about the bars 16a, 18a, 16b, 18b, 16c, 18c and 16dand the controlling action of the floating bars. The weight of the barsand toggle tends to collapse the'linkage so that the bars constantlyfloat on the moving strand and in effect constitute a rate device whichconstantly readjusts its internal flow rate to keep the linkagesuspended and floating so that the delivery rate is equal to the demandof the machine to which the strand is being delivered. Basically thedevice is built around the commonly used equation for wrapping frictionT =T e, where T is the output tension and T is the input tension.Regarding the formula e is a mathematical constant having a value of2.718, ,0 is the co-efiicient of friction and a is the angle of wrap inradians. It can be seen that as the linkage opens up by extension of thetoggle links the total angle of wrap decreases and hence the frictiondecreases and that as the linkage collapses the total angle of wrapincreases with a corresponding increase in friction.

In the formula initial tension T at the incoming end increasesexponentially which is the place in the device for any given change inresistance to flow which will have the greatest effect upon the output TThis relation is attained in this device by the fact that the verticalfloating action of the linkage and bar assembly allows the lowest linkto do the controlling in the normal working range where it is mostsensitive and where the least amount of feedback is required.

Although the linkage itself tends to collapse, it is de sirable for awider range of control to employ auxiliary weights W-W which may, asshown in Fig. 2, be suspended by flexible cords 26-26 from the oppositeends of the uppermost of the bars 16d. Because of the high unbalancedside thrust that the top drag bar imparts to one side of the verticalguide slots 24 considerable friction is set up between the drag bars andthe sides of the slots which reduces the sensitivity of the device.Accordingly, it is preferable, as shown for example in Fig. 10, to hangthe weights W-W on adjustable eccentrics 32-32 mounted on the ends ofthe top drag bar. These eccentrics are rotatable on the bar and may befixed at any desired position by means of set screws 34. By adjustmentof the eccentrics and hence counterbalancing of the side thrust, thefrictional resistance of the bars to movement along the slots may besubstantially nullified so as to greatly increase the sensitivity of thedevice.

In order to make the device produce a controllable initial tension inthe lowest and most sensitive drag bar region the device may bemodified, as shown in Fig. 3, by the addition of a fixed drag bar 23mounted between the upright 15, spaced from and parallel to the otherbars so as to lie outside the knee of the first toggle. As thusconstructed, the strand to be tensioned is drawn over the guide bar 28and beneath the bar 16a before it passes upwardly about the bar 18athereby to provide a floating loop a which is closed by movement of thebar 18a downwardly to and below the level of the bar 28 as the linkagecollapses to bring portions of the loop into surface contact. Thisresults, in a sensitive and yet powerful controlling action by theresult of the contact of the strand surfaces that are moving in oppositedirections. Hence, the floating guide 18a affords most of the control byallowing relatively large changes in the flow rate to occur fromrelatively small feedback forces and displacement.

Under these conditions the device has the ability to correct thevariations in the co-efficient of friction (such as variations in theamount of talc on the ribbon) or other conditions which change thefrictional resistance of the ribbon to movement, as well as minor snarlsand binds of the ribbon in the container. A binding in the container,for example, would cause an increase in the initial tension T and hencea decrease in the internal flow rate. This immediately results incausing the linkage and its weights to move upwardly and the pressure onthe floating loop a and the angle of wrap of the strand about thesuccessive drag bars to decrease, which in turn causes a transfer ofadditional pull on the strand in the container. If complete release ofpressure and wrap on the loop is insufficient to free the binding, thatis, the resistance of the strand to leave the container, the link andweights continue to rise and to decrease the angle of wrap of theremaining bars until the links are in their wide open position, as shownin Fig. 4. In most devices the drag bar diameter to the link span ratiois large, hence an appreciable angle of wrap still exists on the barseven in the wide open position. Under certain circumstances, however, itmay be desirable to reduce the angle of wrap so as to further reduce thefrictional resistance to movement, hence as shown in Fig. 5, the ends ofthe lower bars 16a, 18a, 16b, and 18b, the four lowermost shown in thatfigure, may be offset from the link centers with the result that thereis even less angular contact of the strand with the bars when thelinkage is in its open or extended position. In Fig. 2, the strand haslittle more than tangential contact with the successive bars.

In order to prevent the links of the toggles from falling over to thewrong side of the guide slots, that is, to keep all of them in the sameplane and on the same side of the guide slots, stops are mounted on thetoggles at their knees. These stops are in the form of lugs 30 (Fig. 9)welded or otherwise fastened to the upper ends of the toggle links 20a,20b and 200, for engagement with the lower ends of the toggle links 22a,22b and 22c.

If in the extended position of the linkage there is a sudden release oftension from the container 14, it is alg. riiost instantaneously takenup by the rapid' collapse of the linkage and no large overfeed ortension loss occurs. This self-adjusting to the resistance of the strandto be pulled from the container and the ability to transfer some of itsinternal energy to the container is of great practical importance as itprevents minor ingoing disturbances from growing exponentially intolarge percentage changes in the output. Any disturbance at the ingoingend which causes even small amounts of overfeed will cause the togglelinks to move downwardly and thus reduce the internal flow rate. Thistakes place by downward movement which first increases the wrappingangle and. pressures on the loop a which passes about the drag bar 28,the lowermost floating bar 18a and the pivotally fastened bar 16a. Ifthis is insufiicient to reduce the flow rate to the desired value, thenthe bar 18a drops into contact with a final stop or snub bar 33 whichprovides a pinching action on the counter-flowing portions of thestrand. If at this point the controlling action is still insufficient tobring the flow back to normal, then the next higher pair of linkssuccessively begin to fold and increase the angle of wrap. When all ofthe bars of the linkage are completely collapsed the maximum restrainingvalue of the device is reached. This condition has proved to be morethan ample to prevent any further overfeed. When collapsed, the devicehas been able to stand for weeks without loss of tension in the strand.

If desired the extent of opening of the uppermost toggles, that is,separation of the two uppermost drag bars 16c and 16d may be limited bymeans of cords 36 connected between these bars. These cords, of course,do not interfere with collapse of the linkage. By limiting theseparation of the upper drag bars a certain amount of adjustment for thetotal drag is provided.

A better way of obtaining the adjustment however, in a way which iseasier to set up for making the device use- 111 for various tensionranges, is to place at the input end a pair of parallel guide or dragbars 3838 (Fig. 6). These bars, as seen in Fig. 7, are fixed in spacedparallel relation to each other by end plates 4040, and the latter haveextending therefrom trunnions 4242 journaled in the frame uprights, sothat the device may be rotated about a horizontal axis. One of thetrunnions 42 has a crank 44 extending from it so as to enable rotationof the bars 3838 to any angular position and a thumb screw 45 for fixingit at the desired position of adjustment. With this arrangement thestrand is drawn upwardly over the outermost of the bars 38, and thenceinwardly under the second of the bars 38 and from thence upwardly aboutthe fixed guide 28. This arrangement is especially useful for keepingthe device working in its most sensitive zone as the level of theincoming strand drops in its container.

The device has a tendency to surge when the feeding rate is rapid whichresults in repeated bouncing of the linkage and accordingly it isdesirable to add to the device a drag bar 46 (Fig. 6), supported betweena pair of arcuate arms 48, which in turn are fast to the lowest pair oftoggle links 22a. The bar 46 is parallel to the linkage bars and at theopposite side of the pivotally fastened bar 16a from the bar 28. Whenthe bar 46 is employed, the strand S is looped from the bar 28 about thebar 46 rather than the bar 16a so as to provide arelatively larger loopb. Its action is such that at any time the linkage is rising the storedup loop of relatively large size can quickly be given up in thedirection of flow of the strand without having to drag it out of thecontainer, thus eliminating shock by resistance of the strand to feedfrom the container until it has had a chance to pick up motion. Duringthe collapse of the linkage the motion of the bar 46 is such as to tendto pull back and take out of the flow a length of the strand. Thisbehavior is always out of phase with any vertical disturbance and tendsto dampen it.

a It is evident that each successive tension'zone has a progressivelyhigher tension in it and this adds ,anotherde sirable feature to thedevice which is especially useful in simple wire or rod, such a wirebeing shown at 50 in Figs.

6 and 7. One isthat when the ribbon is being split at a too low tensionroll-over results, that is, the carrying over and eventual breaking ofone strand to the wrong side of the splitter bar. This can be cured byraising the tension value before attempting to split it. The otherdifficulty appears when the splitting is attempted at an extremely hightension, for example, at approximately maximum elongation. Under theseconditions the rebonding seems to lock the individual strands togetherso tenaciously that the strands tear and break instead of splitting. Inbetween the two extremes of too little or too much tension an idealsplitting condition can be obtained. It is evident that such a conditionmay readily be found at one of the tension zones of the device and thatthe splitter bar may then be arranged next to the bar in that zone. Onealternate position of the splitter bar is shown in broken lines 50a(Fig. 7).

While the term strand has been employed herein in the description of theoperation of the device, it is to be understood that it is equallyuseful for reducing and regulating tension in any flexible elongateelement, whether it is in ribbon, strip or sheet form. Furthermore,while textile machines have been mentioned as the place of delivery ofthe strand, it is to be understood that the delivery may be made to anymachine or operation to which a. continuous strip is to be fed.

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includes all modificationsand equivalents which fall within the scope of the appended claims.

I claim:

1. In a device for producing a substantially uniform' tension in anelongate element travelling continuously from a place of storage to aplace of use, a plurality of spaced parallel drag bars through which theelement is woven so that successive courses of the element alternatebetween the bars from one side of one bar to the opposite side of thenext, said bars being comprised of a first set of parallel bars, a basesupporting said first set of bars for translatory movement thereon, toincrease their spacing, and a second set of parallel bars, meanspivotally supporting each bar of the second set of parallel bars betweena pair of adjacent bars of the first set, so that an extension of thefirst set of bars to increase their spacing moves the bars of the secondset toward the plane of the first set, and contraction of the first setto decrease the spacing moves the bars of the second set away from theplane of the first set, said bars in the first set being moved away fromeach other by an increase in tension between the entrance and exit endsof the element, and toward each other by a decrease in the tensionbetween the entrance and exit ends of the element.

2. In a device for producing substantially uniform tension in anelongate element travelling continuously from a place of storage to aplace of use, a base, a plurality of spaced parallel drag bars, throughwhich the element is woven so that successive courses of the elementalternate between the bars from one side of one bar to the opposite sideof the next, links pivotally connecting the bars so that the spacingbetweenbars may be increased by straightening the links and decreased byfolding the links, means pivotally fastening an end bar to the base, andguide means on the base with which every other bar commencing with thepivotally fastened bar is engaged and constrained for translatorymovement in a predetermined path, the intermediate bars being free tomove to and from the plane of the guided bars as the latter are moved intranslation in one direction to increase their 2,98 1,49&v

linear spacing and decrease their lateral spacing, and in the otherdirection to decrease their lateral spacing and increase their linearspacing.

3. In a device for producing substantially uniform tension in anelongate element travelling continuously from a place of storage to aplace of use, a base, a plurality of spaced parallel bars through whichthe element is woven so that successive courses of the element alternatebetween the bars from one side of one bar to the opposite side of thenext, links pivotally connecting the bars so that the spacing betweenbars may be increased by straightening the links and decreased byfolding the links, means pivotally fastening one end bar to the base andvertically disposed guidemeans on the base with which every other bar isengaged for translatory movement in a predetermined path perpendicularto the base, the intermediate bars being unconstrained except where thelinks join them to the alternate bars, and being free to move to andfrom the plane of the alternate bars as the latter are spread apartalong said path to increase their spacing and moved toward each otheralong said path to decrease their spacing.

4. In a device for producing substantially uniform tension in anelongated element travelling continuously from a place of storage to aplace of use, a base, a plurality of spaced parallel bars, through whichthe element is Woven so that successive courses of the element alternatebetween the bars from one side of one bar to the opposite side of thenext, links pivotally connecting the bars so that the spacing betweenbars may be increased by straightening the links and decreased byfolding the links, means pivotally connecting an end bar to the base, atrack on the base with which the alternate bars are engaged andconstrained to move along a predetermined path, the intermediate barsbeing unconstrained except by the links connecting them to the alternatebars, and free to move to and away from the path of the alternate bar,and means operating on the other end bar to move the alternate barstoward each other to increase the lateral spacing of the intermediatebars with reference to the plane of the alternate bars.

5. In a device for producing substantially uniform tension in anelongate element travelling continuously from a place of storage to aplace of use, a base, a plurality of spaced parallel bars, through whichthe element is woven so that successive courses of the element alternatebetween the bars from, one side of one bar to the opposite side of thenext, links pivotally connecting the bars so that the spacing betweenbars may be increased by straightening the links and diminished byfolding the links, means pivotally fastening an end bar to the base, atrack on the base, with which the alternate bars are engaged andconstrained to move along a predetermined path, the intermediate barsbeing unconstrained except by the links connecting them to the alternatebars and free to move to and away from the path of the alternate bars,and means connecting the other end bar and the alternate bar next to itwhich limits separation of said bars.

6. In a device for producing substantially uniform tension in anelongated element travelling continuously from a place of storage to aplace of use, a base, a plurality of spaced parallel drag bars, throughwhich the element is woven so that successive courses of the elementalternate between the bars from one side of one bar to the opposite sideof the next, links pivotally connecting the bars so that the spacingbetween bars may be increased by straightening the links and decreasedby folding the links, means pivotally connecting one end bar to thebase, guides on the base with which the alternate bars are engaged andconstrained to move along a predetermined path, the intermediate barsbeing unconstrained except by the links connecting them to the alternatebars and being free to move to and from the path of the alternate bars,and a snubbing bar fixed to the base on a radius extending from thecenter line of the one end bar, parallel thereto, and spaced therefromby a distance which is greater than the length of the link joining theone end bar and the adjacent intermediate bar, by an amountsubstantially equal to twice the thickness of the element, said snubbingbar supporting a length of the element extending about it from a sourceof supply, and from it tothe underside of the one end bar in a positionto be engaged by a length of the element passing in an oppositedirection about the lowermost of the intermediate bars when thelowermost links are partially folded.

7. A device for producing substantially uniform tension in an elongateelement travelling continuously from a place of storage to a place ofuse, a base, a plurality of spaced parallel drag bars, through which theelement is woven so that successive courses of the element alternatebetween the bars from one side of one bar to the opposite side of thenext, links pivotally connecting the bars so that the spacing betweenthe bars may be increased by straightening the links and decreased byfolding the links, means pivotally connecting one end bar to the base, aguide on the base with which the alternate bars are engaged andconstrained to move along a predetermined path, the intermediate barsbeing unconstrained except by the links connecting them to the alternatebars and free to move to and from the path of the alternate bars, and apair of vertically spaced snubbing bars fixed to the base on differentradii extending from the center line of the one end bar, one of saidsnubbing bars being spaced from one end bar by a distance which isgreater than the radial distance between the one end bar and theadjacent intermediate bar by an amount at least equal to twice thethickness of the element and the other by a distance corresponding tothe radial distance between the one end bar and the adjacentintermediate bar, said snubbing bars being situated above and below ahorizontal plane passing through the axis of the one end bar, the upperone of the snubbing bars supporting a length of the element extendingabout it from a source thereof, and from it to the underside of the onebar in a position to be engaged by a length of the element travelling inthe opposite direction about the lowermost one of the intermediate bars,and said lower one of the snubbing bars supporting the intermediate barin its lowermost position, and pinching the oppositely travellinglengths of the element thercbetween.

8. In a device for producing substantially uniform tension in anelongate element, comprised of a plurality of strands adhering edge toedge in sheet form, travelling continuously from a place of storage to aplace of use, a base, a plurality of spaced parallel drag bars, throughwhich the element is woven so that successive courses of the elementalternate between the bars from one side of one bar to the opposite sideof the next, links pivotally connecting the bars so that the spacingbetween bars may be increased by straightening the links and decreasedby folding the links, means pivotally connecting an end bar to the base,a track on the base with which the alternate bars are engaged andconstrained to move along a predetermined path, the intermediate barsbeing unconstrained except by the links connecting them to the alternatebars and free to move to and from the path of the alternate bars and asplitting bar removably attachable to one of the alternate bars betweenany pair of alternate bars for intercepting the element and separatingit into its constituent strands.

9. In a device for producing substantially uniform tension in anelongate element, comprised of a plurality of strands adhering edge toedge in sheet form, traveling continuously from a place of storage to aplace of use, a frame, a plurality of spaced horizontal alternate andintermediate drag bars through which the element is woven so thatsuccessive courses of the element alternate between the bars from oneside of one bar to the opposite side of the next, means mounting saidintermediate bars for movement toward and away from said alternate bars,said mounting means being pivoted so that the weight of saidintermediate bars and mounting means moves said intermediate bars awayfrom said alternate bars to increase the contact area between theelement and each bar, said weight-induced movement being opposed bytension developed in the element as it travels from one end to the otherin its course between the bars, a splitter bar adapted to be disposedtransversely of the direction of travel of the element at differentpositions of tension developed in the element along its course forintercepting and separating the alternate strands of the element, anauxiliary weight operating on the bars to augment the weight of saidintermediate bars and mounting means to move said alternate andintermediate bars apart, and a snubbing bar fixed to said framesupporting one of said intermediate bars at a 15 2,662,264

10 predetermined position and pinching the elongate element therebetweento maintain tension on the element in said position.

References Cited in the file of this patent UNITED STATES PATENTS1,021,919 Crawford Apr. 2, 1912 1,022,512 Sipp Apr. 9, 1912 1,024,605Singleton Apr. 30, 1912 1,130,642 Spofiord Mar. 2, 1915 1,229,101Linfoot June 5, 1917 2,402,653 Clark June 25, 1946 2,515,902 Silcox -2July 18, 1950 2,571,678 Burns Oct. 16, 1951 Campbell Dec. 15, 1953

